The present invention relates to optical scanners and more specifically to a dual aperture optical scanner.
Optical scanners are well known for their usefulness in retail checkout and inventory control. Optical scanners generally employ a laser diode, the light from which is focused and collimated to produce a scanning beam. An optical transceiver directs the beam against a mirrored polygon or spinner and then against a plurality of stationary mirrors, and collects the beam after it is reflected by a bar code label. A motor rotates the mirrored polygon, and a detector receives the returning beam. The pattern produced by such a scanner is characterized by lines oriented at various angles to one another.
Typically, optical scanners emit light through one aperture, either horizontal or vertical, but not both. In high performance scanners, light is emitted from several directions through this aperture. In the case of horizontal apertures, a pattern of light is projected onto the front and bottom surfaces of a labelled item. In the case of vertical apertures, a pattern of light is projected onto the front and side surfaces of a labelled item. In low performance scanners, light illuminates only the surface which is facing the aperture.
Unfortunately, scanners having one aperture require item orientation to ensure that the bar code label is properly aligned in relation to the aperture. Orientation time slows item throughput and therefore customer throughput. Item orientation may also cause repetitive strain injury.
Therefore, it would be desirable to produce a high performance optical scanner having two scanning windows which illuminate the bottom and sides of a labeled item, thereby minimizing item orientation and increasing throughput.
In accordance with the teachings of the present invention, a dual aperture optical scanner is provided. The optical scanner includes a housing having first and second apertures, a laser beam source, a mirrored spinner for reflecting the laser beam in a plurality of directions, and a plurality of pattern mirrors within the housing for reflecting the laser beam from the spinner through the first and second apertures to an article having a bar code label to be scanned.
Preferably, the first aperture is substantially horizontal and the second aperture is substantially vertical to maximize scan pattern coverage and to minimize required item orientation.
The optical scanner also includes an optical transceiver for passing the laser beam and for collecting reflected light from the scanned article and a photodetector for generating signals representing the intensity of the light reflected from the article.
It is a feature of the present invention that the mirrored spinner and pattern mirrors combine to produce a plurality of scan lines which pass through the horizontal and vertical apertures. The scanner produces a scan pattern which more effectively covers multi-sided articles than single aperture scanners. The mirrored spinner includes three facets which are oriented at different angles with respect to a predetermined reference. The pattern mirrors are flat and include a first set of mirrors for reflecting the laser beam from the spinner and a second set of mirrors for reflecting the laser beam from the first set of mirrors to the article.
Preferably, the optical scanner produces twenty-four scan lines.
It is accordingly an object of the present invention to provide a dual aperture optical scanner.
It is another object of the present invention to provide a dual aperture optical scanner in which a first aperture is substantially vertical and a second aperture is substantially horizontal.
It is another object of the present invention to provide a dual aperture optical scanner which maximizes the illuminated surface area of an article to be scanned.
It is another object of the present invention to provide a dual aperture optical scanner which employs a single laser and motor.